The confOPTIMIZE macro sets the command-line switch that will be passed to the C-language compiler to tune its optimization. This macro assigns a value to the O= Makefile directive. Normally, it is correctly set for your site in your devtools/OS file.

One reason to change optimization might be to track down a bug that is causing your installation of sendmail to core-dump. Just add this line to your site file, and re-Build with -c:

define(`confOPTIMIZE', `-g')

The -g switch causes the compiler to produce a binary that can later be debugged with a symbolic debugger.

Most often, sendmail core dumps are caused by improper builds. Always be sure to keep your system and compiler #include files up to date and in synchronization with their corresponding libraries.

Note that the confOPTIMIZE macro is not the proper place to set other compile-time macros. Instead use confENVDEF (confENVDEF and conf_prog_ENVDEF).